Thermal actuator and method of making

ABSTRACT

An article of manufacture formed of a plurality of layers of deposited metal with the layers being separated by interface layers which render the deposited metallic layers relatively movable under sheer stress to effect damping and decreased force deflection rate. In one preferred embodiment of the invention the article can take the form of a bellows defining a closed volume and having a core formed of thermal material having solid and liquid phases and affording substantially different displacements as a function of temperature.

United States Patent Bucalo [451 Sept. 12, 1972 [54] THERMAL ACTUATORAND METHOD OF MAKING [72] Inventor: Louis Bucalo, 135 Roberts St.,Holbrook, NJ. 11741 [22] Filed: Oct. 12, 1970 [21] Appl. No.: 80,229

Related US. Application Data [63] Continuation of Ser. No. 854,024, Aug.25, 1969, abandoned, which is a continuation of Ser. No. 584,037, Sept.12,1966, abandoned, which is a continuation-in-part of Ser. No. 426,238,Jan. 18, 1965, abandoned.

[52] US. Cl. ..60/23, 29/ 156.4, 252/792, 252/794 [51] Int. Cl ..F0lk25/02 [58] Field of Search ..60/23; 29/156.4

[56] References Cited UNITED STATES PATENTS 2,115,501 4/1938 Vemet..60/23 2,128,274 8/1938 Vemet ..60/23 3,041,821 7/1962 Lindberg, Jr..60/23 3 ,O99,222 7/1963 Poliseo ..60/23 3,183,672 5/1965 Morgan..60/23 X 3,187,639 6/1965 Kelly et al ..204/9 X Primary ExaminerMartinP. Schwadron Assistant ExaminerA. M. Ostrager Attorney-John C. McGregorand James A. Eisenman [57] ABSTRACT An article of manufacture fonned ofa plurality of layers of deposited metal with the layers being separatedby interface layers which render the deposited metallic layersrelatively movable under sheer stress to effect damping and decreasedforce deflection rate. In one preferred embodiment of the invention thearticle can take the form of a bellows defining a closed volume andhaving a core formed of thermal material having solid and liquid phasesand affording substantially different displacements as a function oftemperature.

5 Claims, 21 Drawing Figures .PATENTEBSEP 12 I972 SHEET1UF3 .690.065

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SHEET 3 BF 3 FIGJZA INVENTOR. LOUIS BUCALO v ATTORNEYS THERMAL ACTUATORAND METHOD OF MAKING This is a continuation of Ser. No. 854,024, filedAug. 25, 1969, now abandoned, which was a continuation of Ser. No.584,037 filed Sept. 1966 now abandoned, which was a continuation-in-partof Ser. No. 426,238, filed Jan. 18, 1965 now abandoned.

This invention relates to precision products formed of laminations ofdeposited metal, including variable shims, and various flexing membersand as springs, bellows, diaphragms, couplings or the like, and tomethods for the manufacture thereof.

Precision shims are used in the assembly of high precision equipment andinstruments. The bearings of miniature gyroscopes, synchro motors andpumps, for example, must be set to extreme tolerances. One present daytechnique for precision shiming is based on the use of laminated shimsbuilt up of a plurality of layers, each of foil thickness and in whichthe foil layers can be successively peeled off to reduce the shimthickness by precise increments. As a practical matter, however, thethickness of each foil layer is large in relation to the precisiondemands of present day instrumentation. Moreover, it is difficult,particularly in the case of foil thicknesses of minimum size, to peelthe foil without damaging the shim either by scarring, distorting, orthe like. Moreover, it is often necessary to utilize supplementaladhesives between shim layers to insure the integrity of the product andsuch adhesive layers further reduce the precision and accuracy of theshim dimensions and the increments of change thereof.

In addition to their variable dimension characteristics, which renderthese products particularly suitable for use as precisely variableshims, they also exhibit unusual flexing characteristics deriving alsofrom the unique laminates structure in which a controlled, releasablebond obtains between deposited 'metal layers. There is a notabledecrease in force deflection rate for a given thickness of the laminatedproduct. Also, an inherent damping capacity is achieved as a result ofthe degree of bonding between deposited layers. Depending on the bondingstrength utilized, the laminated member can act as a single solid memberuntil the shear stresses developed therein match the bonding strengthbetween the layers, after which shearing occurs which provides unusualcompliance with attendant increased damping, or hysteresis. Thesecharacteristics make such laminated members particularly useful for useas resilient devices, such as bellows, bourdon tubes, diaphragms,couplings, and other thin wall flexing members.

Accordingly, it is an object of the present invention to provide alaminated, deposited-metal structure in which the deposited metalliclayers are united across interface layers which effect a preciselycontrolled bond therebetween capable of being released to effect eitherremoval of one or more layers or controlled relative movement betweenlayers so that either the dimensions of the member or its forcedeflection rate, or both, are precisely determined.

It is another object of the present invention to provide a product whichis particularly useful as a precision variable shim in which incrementsof reduction of shim thickness can be made extremely small.

It is another object of the present invention to provide an improvedprecision shim which is capable of being reduced in dimension byprecisely controlled increments of extremely small thickness withoutincurring distortion or other mechanical damage in the process ofreducing the shim thickness.

Another object of the invention is to provide a shim capable ofprecision incremental reductions in thickness which is entirely metallicin its construction and free of adhesive layers and other materialswhich are relatively incapable of dimensional control.

Another object of the present invention is to provide a precisionlaminated product of deposited metal which can be economicallyfabricated in a wide range of shapes without sacrificing economy andaccuracy.

Another object of the invention is to provide deposited metal, laminatedproducts of various shapes in which long life under flexing conditionsis obtained, and improved methods for making same.

Another object of the invention is to provide improved flexing products,such as bellows, bourdon tubes, diaphragms, couplings and the like, andimproved methods for making same.

Another object of the invention is to provide a hermetic rotary sealcapable of transmitting motion between two areas without any openingsbetween the areas.

Still another object of the invention is to provide an actuator capableof yielding a positive displacement in response to temperature changes.

In accordance with the present invention a precision laminated productis fabricated by preparing a base or mandrel of metal, wax or othermaterial and applying successive layers of metal by electrodeposition,catalytic deposition, vapor deposition or combination thereof or othertechniques of metallic deposition. The deposited metal is applied inthin layers separated by interface layers of another metal or an oxideof metal until the desired total thickness is attained. The interfacelayer can be extremely thin, of the order of several molecules, tocontrol the laminar bond, rendering it releasable or capable ofshearing, as the case may be. In one preferred embodiment an extremelythin coating of a different metal such as copper is applied as theinterface layer and a different metal such as nickel is deposited on thecopper to a thickness of, say, 10,000 of an inch, after which copper andnickel are successively deposited until the desired end productthickness is achieved.

In use, if the product is to be a shim, successive layers are strippedoff as desired to reduce the thickness by controlled increments. In suchcase the nickel layer can be removed in accordance with the invention bymeans, for example, of anodic treatment in a sulfuric acid solution orby chemical stripping such as Enthone N.P. Such stripping actioncompletely removes the exposed nickel layer down to the first barrierlayer of copper which is not affected by either the stripping chemicalor the anodic treatment. The copper barrier is stripped by use, forexample, of chromic acid bath to which the nickel layer beneath isimpervious. For most purposes the copper layer is used as a boundary orshearing layer which is so thin or far beyond the tolerances of the shimthat it is not reckoned in the dimensioning procedure. The nextincrement of thickness reduction is achieved, therefore, by removing thesecond nickel layer and thereafter repeating the processes until theshim is reduced to its desired thickness. Other combinations of metalsand thickness for removal selectively are described below, together withvarious methods and apparatus useful in carrying out the invention.

In addition to their variable dimension characteristics, these productsalso exhibit unusual flexibility and are capable of flexing andabsorbing shocks over an exceptionally long period of continuouscycling. There is a decrease in force deflection rate for a giventhickness of material, and an inherent damping capacity deriving fromenergy dissipating between the layers. Improvements of a high order ofmagnitude in these characteristics for products such as bellows, bourdontubes, diaphragms, couplings, or other thin-walled flexing members overthose formed by conventional methods can be shown. To this end, inaccordance with the invention, the flexing member, such as bellows, canbe formed on a core mandrel which can, if desired, be removed bydissolving or melting or, in one embodiment of the invention the core isformed of suitable temperature responsive material such as wax andretained within a fully sealed bellows to act as an actuating medium,between its solid and liquid phases, for the bellows. Also, the bellowscan be formed integrally and as part of one operation with variousmounting parts, bosses, bearings or the like.

The above and other features and objects of the present invention willbe apparent from the following specification describing preferredembodiments and taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a schematic view in cross section of a member formed inaccordance with the present invention which is particularly useful as ashim;

FIG. 2 is a schematic view in cross section of a modified shim design;

FIG. 3 is a schematic view in cross section illustrating one method offabricating a precision shim in a complex shape;

FIG. 4 is a view in transverse section of a circular shim;

FIG. 5 is a schematic view in vertical section illustrating a number ofapplications of shims formed in accordance with the present invention;

FIG. 6 is a schematic view illustrating another application of theinvention;

FIG. 6A is a view in enlarged scale of a portion in vertical section ofFIG. 6;

FIG. 7 is a diagrammatic view in distorted scale of a portion of thewall of a flexing member, such as a bellows, formed in accordance withthe present invention;

FIG. 8 is a view in longitudinal section showing a flexible couplingelement;

FIG. 9 is a view in longitudinal section showing a modified arrangementof a bellows or coupling member.

FIG. 10A is a side view ofa mandrel on which a flexible coupling ordiaphragm can be formed;

FIG. 10B is a view in longitudinal section of a diaphragm formed on themandrel of FIG. 9;

FIG. 10C is a view in longitudinal section illustrating a technique forachieving different thicknesses in different parts ofa flexiblediaphragm;

FIG. 10D is a view in longitudinal section showing a finished couplingelement;

FIG. 11 is a view in longitudinal section of a modified couplingelement;

FIG. 12A is a view in longitudinal section of a temperature responsivedevice or thermal actuator formed in accordance with the presentinvention;

FIG. 12B is a view in transverse section of another form of thermalactuator;

FIG. 12C is a view in longitudinal section of a thermal actuatorembodying a resistance heater;

FIG. 12D is a view in side elevation of another form of thermalactuator;

FIG. 13 is a view in longitudinal section of a rotary actuator in whichthe driving and driven ends are hermetically sealed one from the other;and

FIG. 14 is a view in longitudinal section of a hermetic seal memberwhich can be used to convert a conventional toggle switch to ahermetically sealed switch.

Referring first to FIG. 1 of the drawing, the invention is illustratedas embodied in a laminated member particularly useful as a shim, whichis shown in highly enlarged scale and which includes a base or mandrel10, having formed thereon a plurality of layers of metal in sheet form.These metal layers are applied to the base 10 by means of metaldeposition, such for example as electrodeposition, catalytic deposition,vapor deposition, vacuum deposition or combinations thereof. All of suchmethods are well known in the art and the specific details form no partof the present invention. In the illustrated arrangement alternatelayers 11, 12 and 13 are formed of one metal and the other layers 14, 15and 16 of another metal. Such metals can be selected from among copper,nickel, silver and gold. It will be understood that the two or moremetals can be alternated until an initially desired thickness is builtup. In the case of a shim the thickness is the desired characteristic;in the case of a flexing member the deflection is the desiredcharacteristic.

The entire shim material in the form of deposited layers can either beremoved from the base 10 or left bonded to the base which then becomespart of the finished product. In one preferred embodiment the layers ll,12 and 13 represent interface layers or coatings and take the form of athin flash of copper of the order of 10 millionths of an inch or severalmolecules thick and layers 14, 15 and 16 are formed of nickel depositedto a thickness of approximately 0.010 inches. The base 10 can be formedof brass or zincated aluminum.

When using electrodeposition as the deposition method, the basematerial, such as brass, is first plated by conventional strip platingtechniques with a thin flash coating of the first material, such ascopper, approximately 0.00001 (10 millionths) inch thick. A copperfluoroborate, copper cyanide, copper cyaniderochelle, copperpyrophosphate or copper sulfate baths are examples of the types ofplating baths that can be used. Typical compositions of the baths aregiven in Electroplating Engineering Handbook, edited by Graham. Theplated strip is then cut into the desired length and width smallerstrips. The outside edge of the larger original strip may be wasted ifthe deposit on the corners is too large.

In the example just given, copper is used just as a coating or interfaceto form a barrier to the chemical stripping action between layers in thecase of shims or as a shearable bonding layer in the case of flexiblemembers. The actual thickness variation is achieved by chemicallystripping the second thicker layer material. Copper need not, however,be limited to a barrier layer function. It also can be plated todifferent thicknesses and used to vary the total thickness of the shimor to vary the shear characteristics.

The basic construction can be cut, stamped or etched into any desiredconfiguration. In use, the shim can be reduced in thickness by the userin steps which precisely correspond to the thickness of the layers 14,and 16 by placing the shim in a chemical solution that attacks andremoves the outside layer. Thus for example the layer 16 which is formedof nickel can be removed by immersion in stripping fluid such as anorganic oxidizing agent of an ammoniacal base suitable for strippingnickel, such as Enthone N.P. The copper boundary layer 13 beneath thelayer 16 is impervious to the strip chemical whose action is thereforearrested when the entire layer 16 has been dissolved. In this fashionthe shim is reduced by a precisely predetermined amount which can beextremely small relative to conventional machine dimensions. To reducethe thickness a further predetermined amount, the flashing or boundarylayer 13 is removed by a stripper such as CCL COONl-l, or chromic acidafter which the next significant elimination layer 15 can be removed inthe manner set forth above.

To minimize passivation of the layers and insure greater adhesion itwill be understood that the deposition process may be conducted as acontinuous operation in which the base strip is formed as a continuousor can be formed of brass. In this fashion the various layers can beselectively removed using a mixture of nitric aromatic acid salts andcyanides as disclosed in U.S. Pat. No. 3,242,090 and sold under thetrade name McDermid AURO407 solution for removing the gold and asulfuric acid base solution containing nitrates sold under the tradename McDermid CB solution to remove the silver. Large increments ofreduction in dimension can be effected by removing the layers 18 and 19and small increments of reduction by removing the layers 20 and 21successively from the outside inward. Alternatively, the layers on theupper side of the base 17 and the layers on the bottom of the base 17can be formed of the same combination of metals, such for example ascopper and nickel and a masking technique such, for example, asadhesively bonded masking tape can be used to protect the surface whichis not to be removed in cases in which like metals appear on oppositesides of the shim.

Many variations of base material and individual layers may be used inconstructing the shim providing only that the different layers becapable of chemical dissolution without affecting the other layers. Inthe above example the copper layer can be removed in a solution oftrichloroacetic acid neutralized with ammonium hydroxide (pI-l7-9)without affecting the nickel or brass base. A single nickel layer may beremoved by anodic treatment in a sulfuric acid solution or by chemicalstripping. The following series of examples show variations of basicshim materials and stripping chemicals which can be applied for theremoval of the layers selectively and sequentially.

Example Base First Second Third Fourth First Second Third Fourth No.material layer layer layer layer stripper Stripper Stripper stripper 1Brass C CC13COONH4 Enthone NP. CC13CCONI'IJ EntllonoNl. g C rbon steelCu CCIz OONHt d0 CCI3COONII4.. DO. 3 Brass Cu CCl C0ONH4.. McDermidCCIQC()ONII4 McDermid Auro 407. Auro 407 Enthone NI .d0 Enthone NP. Do.

CCl COONH4.. EnthoneNI ..do Do.

CChCOONIIL. do CCISCOONIIL. Do.

. CChCOONHr ..do CCI3COONILL. Enthone NP.

EleetrolessN CClaCOONHt ..d0........... CCI3COONH4.. Do. Ag EnthoneNP.... Chronic acid.. Entho11eNP Chromic acid. Cu Netex CB CChCOONHrNetex CB CClgOOONI'Iq.

) Ni Chromic acid... Enthone NIL... Chromie acid... Enthone NP.

zineated 12 Brass Cu Au N1 Ag CC13COON1I4 MtixDernig; Entlione NPChremie acid.

uro

closed loop and passed successively through the variin the aft, todeposit the correct successive layers as part of one continuousoperation. If less adhesion is' desired, it will be understood thatpassivation can be encouraged.

Referring to FIG. 2 there is illustrated a shim configuration in whichthe base sheet 17 has multiple shim layers of predetermined thicknessapplied to both sides thereof. On the upper side the layers 18 can bealternated with layers 19, both being of predetermined thickness ofrelatively large magnitude and the bottom layers can include alternatelayers 20 and 21 of relatively less thickness and which can be strippedoff to afford very small increments of change in dimension. Fourdifferent metals can be used as, for example, the layers 18 and 19 canbe formed of copper and nickel, and the layers 20 and 21 of gold andsilver. The base 17 It is understood that the thickness of the variouslayers may be independently selected and that the method of depositionmay be electrolytic, autocatalytic or vapor deposition. In most forms ofthe invention presented above the layers are adherently deposited to thebase and to one another thus requiring chemical stripping means forthickness adjustment. In the cases where three or four differentmaterial layers are desired, one side of the base material can be maskedby conventional plating techniques and the several layers deposited onthe other side. When the layers are completed that side is masked andthe masking removed from the base material in order to permit depositsof the layers on the other side.

If the base material is selected so as to provide poor adhesion of thefirst layer, as would be the case of nickel on stainless steel or nickelon a preplated base of nickel-tin, the deposited layers may bemechanically removed from the base as an integral sandwich. It is thenpossible for the base material to be used as a reuseable mandrel ontowhich the shim is repeatedly deposited and mechanically stripped.

A variation of this invention is made possible by changing the sequenceof electrodeposition processes. Conventional laminated shims aremanufactures by cementing thin sheets of metal together. When thethickness of the shim is to be varied for use, the layers aremechanically separated. Mechanically separable layers without adhesiveare attainable in accordance with the present invention as follows:

On a stainless steel strip base a layer of say nickel 0.001 inches thickis deposited. While the strip is in solution a momentary reversal of thecurrent is applied at about 10 ASP for 2 seconds. This reversal willcause nickel hydroxide to form on the strip. Immediately after the 2seconds reversal the direct plating cycle is resumed to form anotherlayer of nickel. This process of direct and periodic reverse plating iscontinued to form the desired number of layers of nickel. However, theimposition of the reverse cycle will render the bond strength of thevarious layers very low. As a result, the layers may be mechanicallyseparated by peeling.

The production of these shims is not limited to strips. The basematerial can be cut, punched, folded, or the like to any desired shapesuch as round, rectangular or elliptical gasket shaped articles beforedeposition. In the cases where this shape precludes the use of a longstrip of the base material, the shims could be individually racked andplated. In other cases the strip base can be masked with rubber cementcompounds, air drying plastic, and/or plastic tapes to plate the stripin the desired shape. The excess base material can then be removed bymechanical or chemical means depending upon the material. If it isdesired to hold the edges of the shim to close tolerances compared tothe center dimension the pieces may be plated at low current densitieslike 2 ASP. For very close edge electroless nickel autocatalytic tocenter tolerances, an electroless nickel autocatalytic solution, alsocalled Kanigen nickel solution, can be used.

The base material can also be in the form of a wire, thus comprising acore. The wire can be removed to produce a hollow tube shaped shim orbearing. If the first layer material is adherent to the wire, the wirecan be removed by chemical etching, for instance aluminum wire can beremoved with sodium hydroxide solution. If the first layer isnon-adherent the wire can be mechanically removed.

Referring to FIG. 3 there is illustrated one technique for achievingpredetermined shim shapes or geometries without necessitating cutting orstamping. To this end the base 22 has affixed to its surface boundarymasks 23 and 24 which delineate precise shape of the shim to be formed.Particle deposition layers 24 and 25 are then applied to the base 22 inone of the various techniques described and the resulting shim isremoved from the base and from the masking elements. Alternatively, thebase 22 can remain attached to the shim structure and if sustained thebase can take the form of a machine part such as a casing of a precisionpump.

Referring to FIG. 4 there is illustrated a shim 25 which is ofcylindrical or tubular form useful for example as a sleeve or bushing.Shim 25 can be formed in accordance with the invention by depositing theprecisely dimensioned layers on a mandrel in the form of a metallic tubeor wire which is thereafter removed by etching, dissolving or bymechanical extraction to leave the final cylindrical shape. Suchcylindrical shim can have its inside diameter increased by removinginside layers or its outside diameter reduced by removing outsidelayers, all in accordance with the techniques described above.

Referring to FIG. 5 there is illustrated a piece of apparatus in whichthree different shim configurations are used. The apparatus takes theform of a gear pump in which the cover plate 26 includes attached edgeshims 27 bonded directly thereto as part of the forming operation and inwhich the drive shaft 27 is received in a shim sleeve 28 correspondingto that of FIG. 4 and in which one of the gear elements is axiallypositioned by a flat, washer-shaped shim 29 which can be either stampedfrom a large sheet or firmed up by the technique of FIG. 3.

Referring to FIG. 6, the invention is illustrated as embodied in aspring 30 which is formed of multiple layers 31 and 32 built up inaccordance with the present invention and which can be successivelyremoved to change the spring constant, which is a function of totalthickness. It will be understood that appropriate selection of layermaterials in the spring 30 can achieve a bimetallic temperatureresponsive spring, the response of which can be varied by removal oflayers in predetermined amounts. It will also be understood that variouselectrical characteristics of a conductor or a member can be similarlycontrolable varied by removing predetermined quantities of materialapplied in layer form across boundary layers.

In addition to having a mechanical control over the springs constant byvirtue of the ability to reduce the thickness by stripping layers, thespring also exhibits unusual characteristics in its behavior by virtueof the controlled bond between deposited metal layers. Because the bondis separable it has certain shear strength characteristics. For example,if the interface or bonding layer is formed of an extremely thin copperflash relative high shear bond strength, of the order of 20,000 psi isachieved when the deposited metallic layers are nickel of the order of0.0002 inches. However, the current-reversing technique in theelectrodepositing process, described previously, develops a nickelhydroxide coating on the previously deposited nickel. This results in abond strength of the order of 1,000 psi between the nickel layers. Thislooser" bond decreases the stiffness or bonding stress by a substantialamount over the copper bond, which is itself a substantial improvementover conventional springs. Applied to bellows, as described below, awide range of response characteristics can be achieved by thesestructures.

Referring to FIG. 7, there is illustrated a wall section 30 of a flexingelement such as a bellows, coupling or other thin-walled member. Thewall in constructed of N layers 31 of metal, such as nickel, eachseparated by a layer 32 of infinitesimal thickness of the order, forexample, of a few molecules. The illustration is not in scale becausethe layers 32 are too thin for scale illustration. The layers 31 can beany metal or alloy capable of being deposited on a mandrel or formthrough electrodeposition, catalytic deposition, vapor deposition,

vacuum deposition, or a combination of these processes, all as describedpreviously. Layers 32 constitute separation or interface layers ofrelatively low shear strength or bonding strength which can take theform of a thin deposition of a different metal such as copper or apassivated surface formed by an oxide coating.

In a specific example, the wall section 30 had a total thickness h of0.005 inches and was formed of layers 31 of 0.0005 inches.Electrodeposited nickel cobalt was used for the layers 31, deposited inthe following manner. The first layer 31 was deposited on an aluminumbellows mandrel which was later removed by dissolving. Following thefirst layer of electrodeposited nickel cobalt a low adherent layer wasgenerated by reversing the plating current for one (1) second at 10 ASF.The following nickel cobalt layers 31 were similarly applied. It wasfound that the layers were so united in a relatively loose bond that thestiffness factor of the finished bellows approached l/N This wasachieved in a single plating bath without removing the work from thebath.

In another example a thin flash layer of copper was used as theinterface layer by deposition in a separate bath. The copper wasdeposited on a thickness of between one and five molecules. In this caseafter breaking the bond by flexing the bellows had a rigidityproportional to h /N each layer again acting separately in respect tobending. Had the product been constructed of a single layer of thicknessh, the stiffness would be proportional to h. Thus in the aboveillustration, the flexibility in the multi-layer construction of 10layers was increased by a factor 100, using layer thicknesses of 0.0005inches.

The thin interface layers 32 can be formed in accordance with theinvention by passivating each of the nickel surfaces after they havebeen deposited to the desired thickness. Passivating can beaccomplished, in the case of nickel, by removing the product from theelectrodepositing bath or other deposition apparatus and dipping it in apotassium dichromate solution. Thus the low bond strength layers can beachieved by chemical means in addition to the other techniquesdescribed. Broadly, passivity is a condition of a metal such that itassumes a potential more noble than its standard potential and thereresults an interface which brings about, in a laminated product ofdeposited metal layers, the useful flexing characteristics describedherein.

It will be understood that members embodying the present invention canbe formed in a wide range of shapes including, for example, a convolutedcylinder closed at its ends and adapted to expand and contract axiallyunder the influence of pressure differentials. The same basic geometrywith certain modifications can also be used for providing flexiblecouplings, and with further modifications, to provide hermetic seals. Tosome extent the unusual spring effects of the laminated members areutilized in each of these products.

Referring first to FIG. 8, the invention is illustrated as embodied in aflexible shaft coupling 33 including a central convoluted flexiblesection 34 and a pair of end fittings 35a and 35b. Shaft couplingstypically require high torsional stiffness, but should also provideflexibility to compensate for shaft misalignment. To this end the wallsof the convoluted'section 34 are formed of a series of layers ofdeposited metal separated by interface layers as shown in FIG. 7 toafford controlled shearing. The polar moment of inertia of the bellowsor coupling 34 about its longitudinal axis or center line is not changedby virtue of the laminated construction. The torque carrying capacity ofthe coupling is therefore unchanged. For the same overall wallthickness, however, the stiffness is decreased by a factor of l/N aboutthe horizontal and vertical axes perpendicular to the center line. Theresulting product therefore has extremely long life and consumesrelatively little energy even under serious misalignment conditions. Thedeposited metal layers can be formed into other shapes to provide otherforms of flexible coupling.

In FIG. 9 there is shown a bellows or coupling in which the flexibleportion is formed of a series of truncated cone sections 36 in the formof laminated members (FIG. 7) stacked together in inverse relationshipand welded at their inside and outside diameters to form a unit.

Referring now to FIGS. 10A-10D, there are shown steps of one preferredmethod for fabricating bellows, flexible coupling or the like,particularly those-having their fittings formed integrally with theflexing portion. In FIG. 10A there is illustrated a mandrel or coreportion 37 which can be formed of aluminum or plastic and on which abellows having two different end configurations can be formed. Thecenter of the core includes the usual convolutions 38, the lefthand end39, a relatively narrow shaft receiving portion and the righthand end 40an end fitting of larger diameter including a radial pin extension 41.In FIG. 10B there is shown deposited metal on the mandrel, preferably inmultiple layers, as described.

If it is desired to form the ends or mounting portions of heaviermaterial, the technique shown in FIG. 10C can be used in which, afterthe last layer of metal has been deposited to the desired thickness toachieve the requisite flexing characteristics in the convoluted portion,a barrier element such as a plastic tube 43 is fitted over theconvoluted section and the assembly returned to the plating bath orother deposition apparatus to build up a thick relatively rigid metallayer on the exposed parts. The mandrel is then dissolved, as by the useof an acid bath and the unit is machined to provide the finishedassembly of FIG. 10D. In this case, by removing both ends, the unitbecomes particularly useful as a flexible coupling. With obviousmodifications in the machining process it could be made into a closedbellows.

It will be understood that various other shapes can be similarlyfabricated to form diaphragms, rupture disks and other complexgeometries such, for example, as the coupling shown in FIG. 11 whichincludes, formed as one integral piece, a pair of mounting end sections44 and 45, a pair of convoluted center sections 46 and 47 bridged by astraight cylindrical section 48. This configuration has been found tocontrol undesired buckling by imparting rigidity to the center. In thisarrangement separate, set-screw clamping collars 44a and 45a are used tosecure the two ends to the two shafts to be coupled.

The invention is illustrated at FIG. 12A as embodied in a thermalactuator in which the excursion and driving force can be augmented bythe use of the encapsulated, temperature sensitive cores. The actuator50 is formed by a deposition of metallic layers (as describedpreviously) on a core 51 of thermal material such as thermal wax or lowtemperature metal having solid and liquid phases. In the depositionprocess, such as the electrodepositing bath, the mandrel is first formedinto the desired core configuration, including convolutions, andmaintained at a temperature which preserves the solid state. The shell50 is electrically deposited in layers, using interface layers so thereresults an encapsulated, temperature sensitive assembly which is voidfree internally and which is capable of expanding or contracting axiallyas a function of the core temperature or phase or both. Most metals andwaxes used for this purpose increase substantially in volume passingfrom their solid and liquid phases, although materials having thereverse behavior are commercially available. The change in phase takesplace at a particular temperature over an extremely short period oftime, so that the actuator will expand axially with great force andprecision at the critical temperature. The fact that the shell iscapable of expanding under very low deflection forces means that highefficiency is achieved. In a typical installation, the assembly ismounted in compression between a fixed reference support and say a valveactuator.

Various other forms and shapes of temperature actuator bellows orcouplings can be provided as shown in FIG. 123 in which a flat diaphragmcapsule is identified by the numeral 52, a bourdon tube by the numeral53. Referring to FIG. 12C there is shown an assembly, identified by thenumeral 54, including an internal heat exchanger in the form of anelectrical resistance heater. The assembly includes a shell 55 filledwith a thermal material such as wax 56, and having imbedded therein aresistance heater 57 adapted to be energized through suitable terminalconnections 58 passing through the shell through suitable insulationbeads 59. When the resistance element is energized the flexiblediaphragm face will snap forward as the core material expands underchanging phase. Thus from a heat or electrical input there is achieved ahigh force output displacement. This is brought about by the ex pansionof the incompressible wax 56 within the shell 55.

Referring to FIG. 13, the invention is illustrated as embodied in ahermetically sealed, rotary actuator assembly which provides aleak-tight seal across which rotary motion can be transmitted. The unit,identified generally by the numeral 60 is shown mounted in a pilot hole61 in a panel or bulkhead 62. An internal rotor assembly 63, including acylindrical base section 64 carrying an axially extended crank arm 65,is rotatably mounted in a bearing 66, preferably formed integrally witha multi-ply metal flexing and sealing member 67. The base or mountingend of the sealing member 67 includes a cylindrical portion 68 having anannular rib 69 on its outer surface, the bearing 66 on its inner surfaceand an elongated, convoluted sleeve portion 70 which envelops the crankarm 65. Carried at the free or remote end of the sleeve portion 70 is anactuating head 71 including an internal cylindrical bearing surface 72,which rotatably receives the tip a of the crank arm 65,- and an indentedportion 73 which rests in an annular groove 65b to secure the sleeve tothe end of the arm. The tip is coupled to a crank arm 74 on an outputdrive shaft 75 by means of a ball 76 received in a socket 77 in the freeend of the crank arm.

The cylindrical portion, 68 fitted into the opening in the panel 62 withthe rib 69 engaging a shoulder 61a, is soldered in place in a fluidtightseal. When the cylindrical drive member 64 is driven in rotary motionthe crank arm 65 will rotate in the bearings 66 and 72 on the sealingmember and will at the same time turn the crank 74 and hence the outputshaft 75 in a direct drive coupling. The flexible hermetic sealingmember 67 will flex in vertical and horizontal planes but will notrotate. The relatively low deflection forces required to flex theconvoluted section 70 permits the drive shaft to be rotated with minimumloss of energy and, because the unit is formed as one integral piecethere are no sliding joints through which leakage can occur. The onlyseal required is the simple solder seal between the fixed bulkhead 62and the cylindrical but non-moving base of the sealing member.

It will be understood that the laminated structure of the integralsealing member 67 is formed on a core in the manner described, withdeposited metallic layers separated by low shear-strength interfacelayers, all as shown in FIG. 7. The material of which the first metalliclayer is formed should be selected to provide a good working bearing,although if preferred, separate bearing sleeves can be interposedbetween the rotary and fixed parts.

Referring to FIG. 14 there is illustrated another embodiment of theinvention by means of which conventional toggle switches can behermetically sealed. A toggle switch 78 is mounted in an opening in apanel 79 by means of conventional clamping nuts 80 and 81 with theactuating finger or bat handle 82 of the switch projecting out of oneend. Fitted over the exposed portion of the toggle switch handle 82 andthe adjacent body portion is a sealing member in the form of a flexiblemulti-layered sleeve 83 including a central convoluted portion 84 and acylindrical mounting end 85 adapted to be welded or soldered to theclamping nut 81 (and also, if desired, directly to the panel 79). Acantilevered sleeve extension 86 on its outer end receives the actuatinghandle 82. Thus the switch can be freely manipulated through a range ofvertical or horizontal positions against the extremely small resistanceof the flexing convolutions. As in the previous embodiments of theinvention, the sealing member is entirely impervious to the passage offluid because it has been formed in a single piece by the techniquesdescribed above.

Other arrangements and embodiments of the invention will suggestthemselves to those skilled in the art. The invention should nottherefore be regarded as limited except as defined by the followingclaims.

I claim:

1. An article of manufacture, comprising a deposited metallic bellowshaving a one-piece, fully closed, continuously uniform, depositedmetallic wall defining a closed aperture-free volume free of sealedaccess openings and capable of expanding in at least one direction; anda solid encapsulated core of thermal material filling said volume as avoid-free mass and onto which the bellows is deposited as an integral,aperture-free unitary structure, said core having solid and liquidphases affording substantially different displacements as a function oftemperature and being permanently contained within the deposited wall,said expandable bellows thereby tracking precisely the expansion andcontraction of the thermal core.

2. An article of manufacture as set forth in claim 1, including heatexchanger means within the core, and means external of the bellows foractuating the heat exchanger to change the phase of the core betweenliquid and solid.

3. An article of manufacture as set forth in claim 2, said heatexchanger comprising an electrical resistance heater.

4. An article of manufacture as set forth in claim 1, said bellowscomprising a metallic member forming a plurality of discrete layers ofdeposited metal of predetermined thickness disposed in overlappinglaminated relation, the respective metal layers being having solid andliquid phases affording different displacements as a function oftemperature, said core having the shape of a bellows, and maintainingthe core in its solid phase while depositing thereon one or more layersof metal to completely encapsulate the core in a fully closed,one-piece, continuous metal shell having the configuration of a bellowsand free of access openings.

1. An article of manufacture, comprising a deposited metallic bellowshaving a one-piece, fully closed, continuously uNiform, depositedmetallic wall defining a closed aperture-free volume free of sealedaccess openings and capable of expanding in at least one direction; anda solid encapsulated core of thermal material filling said volume as avoid-free mass and onto which the bellows is deposited as an integral,aperture-free unitary structure, said core having solid and liquidphases affording substantially different displacements as a function oftemperature and being permanently contained within the deposited wall,said expandable bellows thereby tracking precisely the expansion andcontraction of the thermal core.
 2. An article of manufacture as setforth in claim 1, including heat exchanger means within the core, andmeans external of the bellows for actuating the heat exchanger to changethe phase of the core between liquid and solid.
 3. An article ofmanufacture as set forth in claim 2, said heat exchanger comprising anelectrical resistance heater.
 4. An article of manufacture as set forthin claim 1, said bellows comprising a metallic member forming aplurality of discrete layers of deposited metal of predeterminedthickness disposed in overlapping laminated relation, the respectivemetal layers being separated respectively by interface layers selectedfrom among deposited metal differing from that of the discrete layers oran oxide of a metal, thereby to afford a separable bond between thediscrete layers, said member comprising a hollow unit having a wallportion capable of flexing in at least one direction and in which theseparable bond between discrete layers of the wall portion yields undershear stress of predetermined value to effect damping.
 5. In a methodfor making a metallic bellows, the steps of forming a solid, void-freecore of a material having solid and liquid phases affording differentdisplacements as a function of temperature, said core having the shapeof a bellows, and maintaining the core in its solid phase whiledepositing thereon one or more layers of metal to completely encapsulatethe core in a fully closed, one-piece, continuous metal shell having theconfiguration of a bellows and free of access openings.